The present invention relates to a storage system and control method thereof, and a computer program product.
With a database system that handles enormous amounts of data such as in a data center, data is managed with a storage system such as a disk array system. A disk array device is configured by arranging numerous storage devices in an array and provides the host system with a storage resource in a RAID (Redundant Array of Independent Inexpensive Disks) configuration. The host system and storage system are mutually connected via a device-sharing network such as a SAN (Storage Area Network). As one operation mode of a storage system, Japanese Patent Laid-Open Publication No. 2005-44199 proposes technology of forming a pair among a plurality of volumes distributed and arranged via a network, and performing copies among the volumes. Further, as another operation mode of a storage system, Japanese Patent Laid-Open Publication No. 2005-107645 proposes technology of virtualizing the external storage resource existing outside the storage controller as an internal storage resource so as to seek the effective use of storage resource.